The impedance of an antenna is dependent on the spatial surroundings thereof. This impedance is therefore subject to severe fluctuations, particularly in the case of mobile radios. However, the radiated real power of a mobile radio is heavily dependent on the extent to which the impedance of the antenna matches the impedances of further electric components connected thereto, such as a power amplifier. In addition, the impedance of electric components is also dependent on the frequency of a transmitted signal.
In the mobile radio sector, a plurality of frequency bands is used for signal transmission. To attain a maximum radiated real power, it is necessary to match the impedances in a plurality of frequency bands which are used.
The document U.S. Pat. No. 7,202,747 B2 describes a circuit for impedance matching.